In general, a platform providing an omnidirectional walking interface can be roughly divided into a passive type platform in which a user directly pushes the platform and an active type platform to which a driving source is attached.
Firstly, there is a platform developed by Virtual Sphere Limited as the passive type platform. The platform developed by Virtual Sphere Limited has a hollow large spherical steel structure on a roller with two degrees of freedom, and the spherical steel structure is passively rotated when the user performs a walking operation within the spherical steel structure. Although this passive type platform enables an omnidirectional walking interface to be obtained, a driving source cannot be applied to the platform, and the platform interferes with immersion feeling due to the inertia of the structure when the user is advancing at a high speed, thereby providing a heterogeneous walking floor sense as the floor representation is not flat.
Another passive type platform is an omni pad. However, simply rolling on a sliding pad cannot provide a sense of force like actual walking in a state that the body of the user is constrained.
In the meanwhile, as the active type platform, there is the omnidirectional floor developed and successfully commercialized by MSE weibull. Such an active type platform is configured to place 16 discrete triangular-shaped rollers in a circular form, thereby providing entertainment factors of virtual reality to increase fun. However, when the user is simply away from a central point, the rollers attached to respective segments have only the function of causing the user to move toward the center of the platform by means of rotation of rollers using a motor and cannot support transverse or advancing operations, so that it cannot be considered an interface supporting the omnidirectional walking.
An active type platform that can substantially support the omnidirectional walking is an active type platform developed by the European consortium and an active type platform developed by the US Army Research Laboratory.
In the case of the active type platform developed by the European consortium there is a problem that the power of the motor responsible for Y-axis rotation needs to be significantly increased by attaching a motor to each of the segments for causing the interface to move in the X axis by means of rotation of the segments. In addition, both reactivities of two axes are also decreased due to limitations on the weight of the segment itself for driving the X axis, a complexity thereof, and a small-sized power motor.
In the case of the active type platform developed by the US Army Research Laboratory, it acts as the walking interface in the Y-axis direction through rotation of the segment itself. In this case, rotation of the segments occurs in the X-axis direction in a point friction wheel driving manner that utilizes a plurality of omni wheels on the platform itself instead of a method of attaching a motor to each segment, thereby securing a simpler and higher acceleration and deceleration performance than the an active type platform developed by the European consortium. However, power cannot be reliably transmitted even when a powerful driving source is employed and a very large number of omni wheels need to be driven in order to maintain a consistent friction due to the inefficiency of power transmission of the omni wheels, so that the active type platform developed by the US Army Research Laboratory has a clear limitation on a high performance of acceleration and deceleration interface with respect to the X-axis direction (i.e., a speed equal to or less than 1 m/s2).